Electric plug adapter for connecting in a three phase power circuit



Aug. 25, 1970 GLASSMAN 3,525,971

ELECTRIC PLUG ADAPTER FOR CONNECTING IN A THREE PHASE POWER CIRCUIT Filed July 22, 1968 INVENTOR. Jana/v 64,455,144

United States Patent 01 o:

3,525,971 Patented Aug. 25, 1970 3,525,971 ELECTRIC PLUG ADAPTER FOR CONNECTING IN A THREE PHASE POWER CIRCUIT Aaron Glassman, Scranton, Pa, assignor to Pennsylvania Sewing Research Corporation, a corporation of Pennsylvania Filed July 22, 1968, Ser. No. 746,614 Int. Cl. H01r 3/06 US. Cl. 339-14 3 Claims ABSTRACT OF THE DISCLOSURE An electric plug adapter comprised of (A) a male three phase power cable connector, (B) a female three phase power cable connector, (C) means for holding said male and female connectors in back-to-back relationship, and (D) means connecting the prongs of the male connector with the sockets of the female connector and providing opposite electrical rotation in the male and female connectors. Preferably, the holding means (C) are also the connecting means (D).

BACKGROUND OF THE INVENTION This invention relates to an electric plug adapter for reversing the polarity or direction of rotation of power flowing in a three phase circuit.

It frequently happens that a three phase motor is plugged into a receptacle or cable connector that is so wired as to cause the motor to run backwards because of incorrect polarity of the power flowing to the motor. Of course, either the motor or the receptacle can be rewired so that, when plugged in, the motor will run forwards. This is expensive, time-consuming and frustrating.

To overcome the problem of a backwardly running motor, it has been suggested in US. Pat. No. 2,802,192 to E. E. Johnson to insert in the receptacle an electric plug adapter for reversing the polarity of the power flowing in the circuit. The motor is then plugged into the adapter, thereby providing three phase power of the desired or required polarity.

The adapter described in the cited Johnson patent, while being operative, requires special parts and special construction. An object of the invention is to provide a novel adapter which uses only parts which are already available as cable connectors. A further object is to provide a novel adapter of such simple, compact construction as to permit easy and convenient usage.

SUMMARY OF THE INVENTION The novel three phase electric plug adapter is comprised of a male three phase connector, a female three phase connector and means for holding the connectors in back-to-back relationship. There are also means connecting the prongs of the male connector with the sockets of the female connector and providing opposite electrical rotation in the connectors. The holding means may be the same as the connecting means.

Through this novel assembly of already available parts, the adapter provides a simple, compact construction, permitting easy, convenient and economical usage.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view of a novel adapter.

FIG. 2 is an elevational, sectional view of the novel adapter shown in FIG. 1.

FIG. 3 is a sectional view of the adapter shown in FIGS. 1 and 2 through section lines 33 in FIG. 2.

FIG. 4 is a bottom view of another novel adapter similar to the adapter shown in FIG. 1.

FIG. 5 is a perspective, schematic diagram illustrating the internal wiring of the adapter shown in FIGS. 1, 2 and 3.

FIG. 6 is a perspective, schematic diagram illustrating the internal wiring of the adapter shown in FIG. 4.

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 illustrates a first novel adapter in perspective. It is comprised of a male three phase power cable connector 11 and a female three phase power cable connector 13 held in back-to-back relationship by means internal to the adapter and later to be described. As used herein, the back of the connector is that wall of the connector through which the power cable normally enters the connector. The front of the connector is that side of the connector to which connection is normally made. Thus, the front" of the male connector 11 has prongs 15, 17, 19 and 21 extending therefrom, and the front of the female connector 13 has a wall with slots 71, 73, and 77 through which the prongs of a male connector may be inserted.

FIGS. 2 and 3 show the male connector 11 of FIG. 1 in sectional elevation and sectional plan view. The male connector 11 has a body 23 which includes a back wall 25 and an inner wall 27 on which the prongs 15, 17, 19 and 21 are mounted. A central hole 29 extends through the body 23 from the back wall 25 to the inner wall 27. A fibre disc 31 covers the screw connections 33, 35 (not shown), 37 (not shown) and 39 on the prongs 21, 15, 17 and 19, respectively.

The female connector 13 has a body 4-1 which includes a back wall 43 and an inner wall 45 on which sockets 47, 49, 51 and 53 are mounted. A central hole 55 extends through the body 41 from the back wall 43 to the inner wall 45. There are screw connections 57, 59, 61 and 63 on the sockets 47, 49, 51 and 53, respectively. The sockets are covered by a cap 65 which is held to the base 41 by screws 67 and 69. The cap 65 has a plurality of slots 71, 73, 75 and 77 opposite the sockets 49, 51, 53 and 4 7.

The prong 21 is connected to the socket 53 by an insulated wire 79 by the screws 33 and 63 respectively. The prong 19 is connected to the socket 47 by an in sulated wire 81 by the screws 39 and 57 respectively. The prong 17 is connected to the socket 51 by a screw 61 which extends completely through the two bodies 23 and 41. The ground prong 15 is connected to the socket 49 by a screw 59 which also extends completely through the two bodies 23 and 41. The combination of wires 79 and 81 and screws 59 and 61 hold the connectors 11 and 13 in backto-back relationship, no other holding structure being necessary.

FIG. 5 illustrates the internal circuit of the adapter shown in FIGS. 1, 2 and 3. The four prongs are shown in circular arrangement in the male plane as G (for ground)12-3 (for the phase order of the wires) reading counterclockwise. Then, with the arrangement of wires 79 and 81 and screws 59 and 61, the sockets are shown in circular arrangement in the female plane as 1-G2-3 reading clockwise, thereby providing opposite electrical rotation in the male and female connectors.

In the first embodiment shown in FIGS. 1, 2 and 3, the ground prong 15 is opposite the ground socket 49 so that the screw 59 can connect them straight through. In a second embodiment illustrated in FIGS. 4 (a bottom view) and 6 (a schematic diagram), the ground prong 17a is olfset from the ground socket 49a (not shown). Four wires 79a, 81a, 83 and 85 connect prong-socket combinations 19a-47a, 21a-53a, 17a49a and 15a51a, respectively, with solder joints 33a, 35a, 37a and 39a and solder joints 57a, 59a, 61a and 63a '(not shown). The four wires 79a, 81a, 83 and 85 also hold the connectors 11a and 13a in back-to-back relationship. The use of solder joints provides a mechanically strong structure which is not easily tampered with. Furthermore, the male and female connectors are completely unmodified.

FIG. 6 shows the internal circuit of the adapter shown in FIG, 4. The four prongs are shown in circular arrangement in the male plane as G-123 reading counterclockwise. Then, with the arrangement of wires 79a, 81a, 83 and 85, the sockets are shown in circular arrangement in the female plane as 1-2-3-G reading clockwise, thereby providing opposite electrical rotation in the male and female connections. This second embodiment is otherwise similar to the first embodiment.

The novel adapter may be used in the following manner. When a three phase motor cable is plugged into a receptacle or cable connector and the motor connected thereto runs backwards, the plug is removed. Then, the adapter is inserted into the receptacle or cable connector. Then, the motor cable is plugged into the adapter. With the adapter inserted, the motor now runs forward. The embodiment described above each include a ground wire. If desired, the ground wire may be omitted.

What is claimed is:

1. An electric plug adapter for connecting in a three phase electric power circuit comprising (A) a male three phase power cable connector having a body with a central hole therethrough extending from the back wall to an inner Wall thereof, and a plurality of prongs mounted on said inner wall around said hole;

(B) a female three .phase power cable connector having a body with a central hole therethrough extending from the back wall to an inner wall, and a plurality of sockets mounted on said inner wall around said hole;

(C) means for holding said male and female connectors in back-to-back relationship with the central holes in register;

(D) and means for electrically connecting said prongs with said sockets to provide an electrical rotation in said female connector which is opposite to the electrical rotation in said male connector.

2. The electrical plug adapter defined in 1 wherein there are four prongs in said male connector and four sockets in said female connector.

3. An electrical plug adapter according to claim 1 wherein said means for holding said male and female connectors in back-to-back relationship are also said means connecting said prongs and said sockets.

References Cited UNITED STATES PATENTS 4/ 1953 Robinson et a1 2005l.07 2/ 1964 Hubbell. 

